Rotary throttle blade design



Jan. 19, 1954 J. s. JAQUITH 2,666,618

ROTARY THROTTLE BLADE DESIGN Filed July 29, 1949 FIGB V ,6

@MA l "w I6 l v A INVENTOR. 6 JoH/v s. Mau/TH y BY 'Y I8 Patented Jan,19, 1,954

UNITED STATE-is PArsNrorFlcE ROTARY THROTTLE BLADE DESIGN John S.Jaquith, Caldwell, N. J., assignor to Bcndix Aviation Corporatiocorporation of Delaware Application July 29, 1949 Serial No. 107,490 2oiarms. (o1. 25a-rs) The present invention relates to throttles forrotary turbines, and more specifically to the contour and design of thethrottle blades.

The invention finds particular utility in high velocity aircraft and inaccessories therefor, such as ram airrdriven power supplies, forexample, Where it is desired to .throttle and control the ram flowpropelling a rotor.

in installations of the type where a plurality of circularly disposedfixed vanes guide a ram air stream against the buckets of a turbinewheel to turn said wheel, anda rotary throttle is actuated by a motor tocontrol the ingress of said stream to said vanes, for example, thedesign of the contour of the throttle blades is of paramount importance,for these are 'subject to sudden, and often, unpredictable loadreversals, .high frictional drag, compressib'ility effects, 'shock waveloads, and other aerodynamic disturbances characteristic of transonicland supersonic speed.

In conventionalrctary throttling valves, the blades thereof are usuallyin the form of triangular prisms, i. e., in cross section the blade issubstantially triangular in form having a base portion adjacent thenozzle block and 'sides that converge inwardly toward each 'other tomeet at the apex of the triangle. Thus, the blade is `provided with` arelatively sharp edge that splits 'or divides the incoming airstream andcauses it 'to flow over the side surfaces of the blades.

When the throttle valve is in open position the air stream passes fromthe yside surfaces of the blade into the throat ofthe nozzles, i. e.,the spaces between the stators of the nozzle block. Since the area ofthe throat of the nozzles is substantially less than the area denedbetweentwo adjacent apices of theblades, it is apparent that as theairstream enters the throat its velocity is increased with a result thatthe pressure of thev aix-stream decreases. Ihis phenomena is referred toin the art as Bernoulli eifect."

In instances where vthe stators ofthe nozzle block defining the nozzlesare symmetrically disposed about an axis parallel to the airstream, inthe open position of thethrottle, the airstream splits or 'divides andpasses into the nozzle'throat Without materially I affecting the bladesofthe throttle. However, it has been found that where the stators areunsymmetrical so as to denne curved or 'sinuous nozzles, the pressure ofthe air stream acting on the sloping sides of-the blade are unequal andtherefore produce an .unbalf anced force tending to rotate throttle.

Moreover, vit 'fhas been mfound heretofore that in the operation'o'f:adevice `of Vthe above-,indi-l n, 'Teterbora N. J., a

J2 cated character, as the motor actuates `the throttle from full opento full fclosed position, the load `due .to Bernoull-i effect will insome instances suddenly reverse itself in some intermediate posi- Y tionproximate -to the two-third open position,

thereby causing .instability at the point of re versal and irregularity`of the throttle operation, and necessitating a driving system free ofbacklash, and accordingly, more complicated `and expensive, to overcomethis condition.

It is, therefore, vone of the objects -of the pres ent invention toprovide a novel type -of throttle blade wherein the foregoingydisadvantages are substantially eliminated and to do so by novel andeffective means.

Another object .of the .invention is to provide a novel type blade forarotary ram air throttle, and upon which the throttle l'o'ad due toBernouli-i effect will be reduced to -aminimum `Still another object ofthe inventionA is to pro-y vide a blade for a rotary ram air throttlefree of instability due to the reversing of the load thereon bymaintaining the load always in one direction.

Still another object of the invention is to provide a novel type ofthrottle blade .for a rotary ram air throttle which will permit thethrottle to be actuated by relatively lighter and llowerpowered drivingmeans.

The foregoing and other objects and advantages will appear more fullyhereinafter from a Vconsideration of the detailed description which'tion is illustrated by way of example. It is to be' expresslyunderstood, however, that the drawings are for the purpose ofillustration only, and :are not to be construed as -dening the limits ofthe' invention. l f

Referring to the drawing wherein like reference characters :designatelike parts,

Figure l shows a front View of a rotary throttle.

` Figure 2 is a section through one yof `the blades along the line 2-2of Fig. 1.

Figure 3 isa schematic drawing showing the throttle blades in operatingrelation to the vanes and to the turbine wheel.

. VReferring now to the drawings and more partic-ularly to Figures 1 and3, a rotary throttle, generallyindicatedl by the figure Ill comprises aseries of blades l2- adapted by rotary motion tov As shown in Fig. 2,the blades are substantially in the form of a triangular prism having abase portion I9 that is designed to close the nozzle spaces I4 in theblock i6 and an apex or edge 22 that is adapted to project into andsplit the air stream S so as to pass it over the sloping sides 24 and 2Bof the blade I2. The side 24 of the blade I2 is so contoured thatadjacent the base I9 it merges or blends into the base I9 to form aknife-like edge 28. On the other hand, the side 26 of the blade I2terminates short of the base I9 in a step 3!! to the end that a flatsurface 3l normally disposed to the base I9 is provided. Since this edgeof the blade I2 cuts across the air stream entering the throat 2I duringrotation of the valve in a closing direction, it is usually termed theleading edge of the blade. Thus, the blade I2 is provided at one edge ofthe base thereof with a flat surface 3I that is exposed to the pressureof the airstream flowing through throat 2l, while the opposed edge ofthe base is provided with a relatively sharp knife-like edge 28 that isexposed to the pressure of the airstream flowing through the nextadjacent throat 2 I. Since the flat surface 3l is normal to the airstream, it is apparent the Bernoulli elect thereon will be greater thanthe Bernoulli effect on theknife-like edge 28, and thus a regulatingload is placed on the blade I2.

As the blades I2 move from fully open position in the direction of thearrow A, the air stream strikes the tips of apices 22 of the blades andseparates on either side of the blade I2, thereby creating a pressuredistribution over the side surface 24 and the knife-like edge 28 on oneside of the blade I2 and the side surface 2B and at surface 3i on theother side of the blade I2.

In normal operation with the throttle partially closed as shown inFigure 3, the velocity of the air stream S across the narrow throat 2|is relatively higher than the velocity across the remainder of face 26and face 24. This effect causes the force on face 26 to be lower thanthe force on the corresponding portion of the sloping surface on theopposing side 24. The net component force on face 24 will thereby -tendto further close the throttle.

It will now be apparent to those skilled in the art that as the stream Spasses over the blades I2, the pressure will always be greater on theVsurface 24 containing a knife-like trailing edge, since said edge willpresent only a small area for Bernoulli effect to act upon. The leadingedge 30 is of sufficient thickness so that the load, during movements ofthe throttle from open to closed position, will always over-balanceBernoulli effect in the opposite direction.

It is further apparent that by regulating the height 32 of the step 30,the differential in pres-y sure on the surfaces 24 and 26 may be furtherregulated and controlled.

In this manner, the throttle is susceptible vof being driven by far lesspowered driving means than would ordinarily be employed withoutregulating the Bernoulli effect to aid the driving means. The step 30 inthe leading edge of the blade negates the possibility that the load onthe blade, due to Bernoullieffect, will reverse ltself while the bladeis in an intermediate position between full open and full closedthrottle.

This regulation of the `load uni-directionally re-I sults 1n a morestable and smoother throttle-' There are thus provided means forregulating the actlon of the Bernoullieect. QVQI the. blades.

of a rotary throttle controlling a ram air stream which are positive andreliable in operation, which improve the performance of the remainingcomponents of the turbine, and which are simple and economical tomanufacture.

While only one embodiment and one application of the invention has beenillustrated and described, other changes and modifications of the formand relative arrangement of parts, which will now be apparent to thoseskilled in the art, may be made without departing from the spirit andscope of the invention.

What 'is claimed is:

1.. In the combination of a plurality of fixed, spaced stators definingsinuous inlet nozzles therebetween to receive and direct an airstream toa turbine wheel and a rotary throttle valve having a plurality of spacedblades, each blade being individual to and coacting with one stator andthe inlet nozzle defined by that stator and the next adjacent stator inthe direction of rotation of the turbine wheel, each blade effective onrotation of the throttle valve relative to the stator to move relativeto its coacting inlet nozzle to vary the effective area thereof, animproved blade for the rotary throttle valve, said blade comprising asubstantially prismatic body having a base adjacent its coacting statorand inlet nozzle and a relatively sharp apex extending into theairstream, the sloping surface between the apex and one side of the baseterminating short of the base in a step having a first fiat surfacenormal to the' base and a second flat surface between the rst flatsurface and the sloping surface and parallel to the base and the slopingsurface between the apex and the other side of the base merging into thebase to form a knife-like edge with the base.

2. In the combination of a plurality of xed; spaced stators definingsinuous inlet nozzles theref between to receive and direct an airstreamto a turbinewheel and a rotary throttle valve having a plurality ofspaced blades, each blade being individual to and coacting with onestator and the inlet nozzle defined by that stator and the next Kadjacent stator. in the direction of rotation of tho turbine wheel, eachblade effective on rot-ation of the throttle valve relative to thestator to move relative to its coacting inlet nozzle to vary theeffective area thereof, an improved blade for the rotary throttle valve,comprising a body substantially triangular in cross section and havingthe base thereof adjacent its c-oacting stator andv inlet nozzle, a stepformed on said body at one end of the base and having a first flatsurface extending forwardly from and normal to the base and a secondfiat surface extending normally from the first flat surface toward theopposite end of the base and parallel thereto, a knife-like edge formedon said body at the opposite end of the base,an'd side surfacesextending forwardly from the second flat'surface of said step and saidknifelike. edge and converging toward each other to meet andform arelative sharp-edge for said body, said step forming the leading edge ofsaid blade when said blade moves across the inlet nozzle to decrease theelective area thereof.

, A. l W JOHN s. JAQUiTH.

Y neferenqes Cited in the fue of this patent Number Name Y Date 801,345Svoboda oct. 1o, 1905 $62611 Schulz @Ci-e190?-

